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Magnesium Wheels?

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UltimateQuestion

UltimateQuestion

Jedi Warrior
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Magnesium Wheels?

I have a set of vintage American Racing Specter wheels I bought on eBay a few years ago. They are 13x5.5, prpoer PCD and offset and will look great on my GT6. The wheels seem to be in pretty good shape except they need polishing, but I have some concerns. I was reading on a different board that concentrates on racing topics not long ago and a poster I consider an "expert" said that old magnesium wheels should not be used. (They were discussing some vintage mini-lights)
I'm not sure my wheels are magnesium, but I think they might be - they are extemely light and they have been coated on the inside of the rims with "goop" to seal them. (I have read that magnesium is porous and tends to leak air)
This leaves me with a couple of questions:
How can I tell if these wheels are really magnesium or if they are aluminium?
If they are magnesium, are they safe for street use or for autocrossing?

Thanks,

Tony
 
Re: Magnesium Wheels?

Before I would drive on them, I would take them to a reputable wheel repair center for an opinion. I sold a lot of real mag wheels back in the day and we never used any goop to seal them. I only remember one as being porous and that was debatable at the time. As a matter of fact the guys that ran them hard wanted nothing on the wheel that could affect the balance. One side was as clean as the other.
 
Re: Magnesium Wheels?

I can tell you one way that I remember from Chemistry. You'll have to collect some filings and ignite them. Less than a pencil eraser and the finer the filings the easier to ignite. Magnesium filings give off a white flame and it's very bright, flash bulb bright.
 
Re: Magnesium Wheels?

I purchased a new pair of 8-spoke American magnesium wheels in 1968 for my '67 GT6. They were great and I too sealed the inside because they were porous and leaked air. I used a clear spray that American sold to coat them. Paul is right about some kind of thick "goop". The reason they are not available for road use anymore is because of the fire issue. It was not uncommon for a wheel to ignite if it would skid on the road after a blowout.

This I will say, if anyone likes the aluminum flywheel difference you should experience magnesium wheels. I went from wire wheels with tube tires to mag wheels and tubeless tires. It was incredible!
 
Re: Magnesium Wheels?

If they are Magnesium I have seen them sell for a lot of money. I thought the racers liked them because of that. But this was something I heard years ago and maybe they don't allow them anymore.
 
Re: Magnesium Wheels?

Magnesium wheels have pores, and corrode easily. Moisture gets into the pores and starts the rot, which can spread inside and be totally invisible externally. It's also pretty hard to detect, or rather, it's hard to test wheels and be certain they don't have issues.
So don't use old mag wheels except on a display-only car, and certainly not any genuine old Minilites. In any case, modern aluminium alloys are a lot better than back in the 60s.
 
Re: Magnesium Wheels?

How about the color ? Aren't mag wheels more of a grayish color than aluminum ?
 
Re: Magnesium Wheels?

You guys are right about the rot and the color. They also require a constant attention to clean and spray the exterior with a clear lacquer. If they are left unprotected even for a couple weeks they will start to form a whitish powder coating and loose the nice original finish. They can be cleaned and even polished but the unique original look of the cast magnesium, at least as far as I know, can not be brought back. Even the polished part will not be reclaimed. On mine the 'polished' parts were made when the castings were turned and were not from an actual polishing action.
I always thought their beauty came from the knowing what they were rather than the actual appearance. The uninformed most likely would have chosen pretty aluminum wheels over functional magnesium wheels.
 
Re: Magnesium Wheels?

UltimateQuestion said:
I have a set of vintage American Racing Specter wheels I bought on eBay a few years ago. They are 13x5.5, prpoer PCD and offset and will look great on my GT6. The wheels seem to be in pretty good shape except they need polishing, but I have some concerns. I was reading on a different board that concentrates on racing topics not long ago and a poster I consider an "expert" said that old magnesium wheels should not be used. (They were discussing some vintage mini-lights)
I'm not sure my wheels are magnesium, but I think they might be - they are extemely light and they have been coated on the inside of the rims with "goop" to seal them. (I have read that magnesium is porous and tends to leak air)
This leaves me with a couple of questions:
How can I tell if these wheels are really magnesium or if they are aluminium?
If they are magnesium, are they safe for street use or for autocrossing?

Thanks,

Tony
Click to expand...

Tony This thread may help! American Racing Silverstones
 
Re: Magnesium Wheels?

And I will stand corrected on my previous comments. My referenced time frame was late 60's / very early 70's on that statement about the lack of porosity and then we got out of that part of the business when GM officially (and unofficially) got out of racing.

Having read what I read about the white powdery affect, I do now remember that being a problem later in the 70's and porosity had then started to rear it's ugly head.

My apologies for posting without looking or thinking about the entire history of the magnesium product and the reasons that it is no longer used today. I do remember a car that blew a front tire in a quarter mile drag race at a strip near Pittsburgh and the front wheel was a fireball for quite a while. They nearly lost the car that day.
 
Re: Magnesium Wheels?

Aluminum burns too. It shares many properties with magnesium. It takes more heat to get it going, however.

After the 1989 Oakland, CA firestorm, I had the opportunity to go up into the hills to see what was left. Automobiles were pretty interesting. ALL that was left was steel! Rubber, plastic, glass, paint -- and cast aluminum wheels: all gone. The cars that had steel wheels were still sitting on 'em. The cars with alloys were sitting on the ground!
 
Re: Magnesium Wheels?

You'll find a lot more information on magnesium wheels in aircraft maintenance articles and such than in automotive ones. They are more common there.

Highly corrosive, subject to fatigue fracturs, sensitive to cleaning methods, etc. Personally, if I had a set of genuine old magnesium wheels, I'd sell them to someone who really wants them, and buy new(er) aluminum wheels.
 
Re: Magnesium Wheels?

I never heard that magnesia wheels do burn. They are not pure magnesia just a fragment of the wheel is magnesia, the rest is aluminum.

Cheers
Chris

17389.jpg
 
Re: Magnesium Wheels?

When our barn burned down the fire fighters kept spraying water on the TR-3 and wondered why the fire kept getting bigger.
 
Re: Magnesium Wheels?

Wasn't there a lot of magnesium in Ricky Nelson's DC3 when it burned and crashed??
 
Re: Magnesium Wheels?

tomshobby said:
The American Racing magnesium wheels were all magnesium.
Click to expand...

Pure magnesium wouldn't work because the yield strength of this stuff in pure is not strong enough. Only the combination as an alloy create the needed strength.

If an aluminum wheel would weight 6 kg an pure magnesium wheel would have 4 kg.

But if you alloy aluminum with magnesium you get a lot better metal and can redesign the wheel to get also a 4 kg wheel with aluminum.

There are several technical usable alloys with Mg:

Mg-Al-, Mg-Mn-, Mg-Si-, Mg-Zn- and Mg-Al-Zn.

MG-Si is used for crank housings or gearboxes. Unfortunately they get brittle after some years of use. A common Porsche problem with cars of the 70ties.

Cheers
Chris
 
Re: Magnesium Wheels?

I restored a set of Americans Alloy wheels.
I presume they are "Mag" wheels.

First thing I did was to make sure the wheels were true.
Then I had steel inserts installed to "index" the lug nut holes. You have to make sure the lug nuts holes are round and not oval. These wheels are "lug-centric". If the lug nut holes have been pounded out of shape, then the wheel will run out of center.

Then I had the rims machine polished.
Then I painted the rest of the wheel.

I have had these rims on my car for over a year, 2000 miles. No problem.

If you want, I can email you some pictures.

richards@hollywoodcenter.com [img:center]
TRNEWMAGS-1.jpg
https://[/img]
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Re: Magnesium Wheels?

MadMarx said:
tomshobby said:
The American Racing magnesium wheels were all magnesium.
Click to expand...

Pure magnesium wouldn't work because the yield strength of this stuff in pure is not strong enough. Only the combination as an alloy create the needed strength.

If an aluminum wheel would weight 6 kg an pure magnesium wheel would have 4 kg.

But if you alloy aluminum with magnesium you get a lot better metal and can redesign the wheel to get also a 4 kg wheel with aluminum.

There are several technical usable alloys with Mg:

Mg-Al-, Mg-Mn-, Mg-Si-, Mg-Zn- and Mg-Al-Zn.

MG-Si is used for crank housings or gearboxes. Unfortunately they get brittle after some years of use. A common Porsche problem with cars of the 70ties.

Cheers
Chris
Click to expand...

That is true and also that aluminum wheels are alloys of aluminum. I was referring to the fact that they are one piece construction and not with separate spokes and rims.
 
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